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Chapter 3 Membranes &
Integumentary System (p. 81- 107)
Skin
• Our skin is an organ• It makes up about 15% of your total body weight
• Considered the “Integumentary System” because it…
• Contains glands and sensory receptors
• Grows hair and nails
Membranes
• Surround and help protect the body’s surfaces
• 2 Categories
• 1. Epithelial membranes
• 2. Connective Tissue membranes
Epithelial Membranes
• Provide a lining for internal and external surfaces of the body
• Epithelial membranes are composed of…
• Sheet of epithelial cells
• Underlying layer of connective tissue
Epithelial Membranes
• There are 3 types of epithelial membranes
• 1. Mucous Membranes
• 2. Serous Membranes
• 3. Cutaneous Membranes
Mucous Membranes
• Mucous: slippery solution that protects mucous membranes and aids in transporting substances
• Line body cavities that open to the outside world
• Respiratory tract (nose, lungs)
• Digestive tract (mouth, stomach)
• Urinary tract (bladder)
• Reproductive tract
Serous Membranes
• Serous fluid: a thin, clear fluid that serves as a lubricant between the parietal and visceral membranes to minimize friction and “wear and tear” on organs
• Line body cavities that are closed to the outside world
• Pleura (around the lungs)
• Pericardium (around the heart)
• Peritoneum (around the abdominal cavity)
Cutaneous Membrane
• What we know as “skin”
• Keratinizing stratified squamous epithelium
• Underlying dense fibrous connective tissue
• Dry membrane when sweat is not present
• Contain sweat glands
Connective Tissue Membranes
• The only membrane only made up of connective tissue
• Include no epithelial cells
• Only one type: Synovial membranes
• Line capsules that surround synovial joints (shoulders and knees)
• Serve as cushions for tendons and ligaments surrounding joints
• Synovial fluid: clear fluid which provides cushioning and reduces friction and wear on moving structures
Functions of the Integumentary System
• 1. Protection• First line of defense
• Outermost layer of skin contains keratin
• Tough protein also in hair and nails
Functions of Integumentary System
• 2. Water Barrier• Keratin and natural skin oils serve as a water
barrier
• Lessens evaporation of water
• Prevents water entering body while swimming or bathing
Functions of Integumentary System
• 3. Temperature Regulation• Sweat glands and capillaries lie close to surface of
the skin
• Body is hot capillaries dilate allows heat to leave
• Sweat glands activate, sweat evaporates, skin cools
• Body is cold capillaries constrict blood flow moves toward core of body to minimize heat loss
Functions of Integumentary System
• 4. Vitamin D Production• Melanocytes: specialized cells in the skin that produce
melanin
• Melanin: pigment that protects the body against harmful UV rays
• UVB rays convert modified cholesterol molecules into vitamin D
• Vitamin D: essential for bone health
Functions of Integumentary System
• 5. Waste Elimination• Sweating eliminates chemical waste products from the body
• Urea, uric acid, salts
**Sweat is acidic and helps protect the body against bacterial infections!**
Functions of Integumentary System
• 6. Sensory Perception• Cutaneous sensory receptors are part of the
nervous system
• Transmit nerve signals from the skin to the central nervous system
• Touch, pressure, vibration, pain, temperature